summaryrefslogtreecommitdiff
path: root/libc/sysdeps/linux
diff options
context:
space:
mode:
authorChristophe Lyon <christophe.lyon@st.com>2013-01-18 14:08:04 (GMT)
committerWaldemar Brodkorb <wbrodkorb@conet.de>2018-08-10 14:01:58 (GMT)
commit5ec586eb37f61e57f19ac60b58af61f167ca054a (patch)
tree6c72d03d43e76a33eb5d6360d9bdb2573a048c42 /libc/sysdeps/linux
parentf88bb681ba22d77a19abfb4c1617c826298ed473 (diff)
rtld: Add FDPIC code for arm
Add FDPIC dynamic relocations support, similar to what other FDPIC targets do. Lazy binding is implemented in a folllow-up patch. Disable the SEND* macros because they involve relocations to access constant strings that are unsupported by the existing arm version. Define DL_START, START, ARCH_NEEDS_BOOTSTRAP_RELOCS, DL_CHECK_LIB_TYPE similarly to what other FDPIC targets do. Define raise() because _dl_find_hash references __aeabi_uidivmod, which uses __aeabi_idiv0 which in turn references raise. * include/elf.h (R_ARM_FUNCDESC): Define. (R_ARM_FUNCDESC_VALUE): Define. * ldso/include/dl-string.h (SEND_STDERR, SEND_ADDRESS_STDERR) (SEND_NUMBER_STDERR): Define empty for __FDPIC__. * ldso/ldso/arm/dl-inlines.h: New file. * ldso/ldso/arm/dl-startup.h (PERFORM_BOOTSTRAP_RELOC): Fix type of load_addr. Fix handling of R_ARM_RELATIVE, add support for R_ARM_FUNCDESC_VALUE. (DL_START, START): Define for __FDPIC__. (raise): Define. * ldso/ldso/arm/dl-sysdep.h (ARCH_NEEDS_BOOTSTRAP_RELOCS): Define. (DL_CHECK_LIB_TYPE): Define. (elf_machine_type_class): Take into account FDPIC related relocations. (elf_machine_load_address): Support __FDPIC__. (elf_machine_relative): Likewise. * ldso/ldso/arm/elfinterp.c (_dl_linux_resolver): Dummy support for __FDPIC__, implemented in a later patch. (_dl_do_reloc): Fix reloc_adr computation for __FDPIC__, fix handling of local symbols. Fix handling of R_ARM_RELATIVE, add support for R_ARM_FUNCDESC_VALUE, R_ARM_FUNCDESC. * ldso/ldso/arm/resolve.S: Make _dl_linux_resolve hidden. * ldso/ldso/fdpic/dl-inlines.h (htab_delete): Declare. * libc/sysdeps/linux/arm/bits/elf-fdpic.h: New file, similar to bfin's. * libc/sysdeps/linux/arm/crtreloc.c: Likewise. * libc/sysdeps/linux/arm/find_exidx.c (__dl_addr_in_loadaddr) Define. (find_exidx_callback): Support __FDPIC__. Signed-off-by: Mickaël Guêné <mickael.guene@st.com> Signed-off-by: Christophe Lyon <christophe.lyon@st.com>
Diffstat (limited to 'libc/sysdeps/linux')
-rw-r--r--libc/sysdeps/linux/arm/bits/elf-fdpic.h114
-rw-r--r--libc/sysdeps/linux/arm/crtreloc.c144
-rw-r--r--libc/sysdeps/linux/arm/find_exidx.c38
3 files changed, 296 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/arm/bits/elf-fdpic.h b/libc/sysdeps/linux/arm/bits/elf-fdpic.h
new file mode 100644
index 0000000..3d6db54
--- /dev/null
+++ b/libc/sysdeps/linux/arm/bits/elf-fdpic.h
@@ -0,0 +1,114 @@
+/* Copyright 2003, 2004 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Lesser General Public License as
+published by the Free Software Foundation; either version 2.1 of the
+License, or (at your option) any later version.
+
+In addition to the permissions in the GNU Lesser General Public
+License, the Free Software Foundation gives you unlimited
+permission to link the compiled version of this file with other
+programs, and to distribute those programs without any restriction
+coming from the use of this file. (The GNU Lesser General Public
+License restrictions do apply in other respects; for example, they
+cover modification of the file, and distribution when not linked
+into another program.)
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, see <http://www.gnu.org/licenses/>. */
+
+#ifndef _BITS_ELF_FDPIC_H
+#define _BITS_ELF_FDPIC_H
+
+/* These data structures are described in the FDPIC ABI extension.
+ The kernel passes a process a memory map, such that for every LOAD
+ segment there is an elf32_fdpic_loadseg entry. A pointer to an
+ elf32_fdpic_loadmap is passed in r7 at start-up, and a pointer to
+ an additional such map is passed in r8 for the interpreter, when
+ there is one. */
+
+#include <elf.h>
+
+/* This data structure represents a PT_LOAD segment. */
+struct elf32_fdpic_loadseg
+{
+ /* Core address to which the segment is mapped. */
+ Elf32_Addr addr;
+ /* VMA recorded in the program header. */
+ Elf32_Addr p_vaddr;
+ /* Size of this segment in memory. */
+ Elf32_Word p_memsz;
+};
+
+struct elf32_fdpic_loadmap {
+ /* Protocol version number, must be zero. */
+ Elf32_Half version;
+ /* Number of segments in this map. */
+ Elf32_Half nsegs;
+ /* The actual memory map. */
+ struct elf32_fdpic_loadseg segs[/*nsegs*/];
+};
+
+struct elf32_fdpic_loadaddr {
+ struct elf32_fdpic_loadmap *map;
+ void *got_value;
+};
+
+/* Map a pointer's VMA to its corresponding address according to the
+ load map. */
+static __always_inline void *
+__reloc_pointer (void *p,
+ const struct elf32_fdpic_loadmap *map)
+{
+ int c;
+
+#if 0
+ if (map->version != 0)
+ /* Crash. */
+ ((void(*)())0)();
+#endif
+
+ /* No special provision is made for NULL. We don't want NULL
+ addresses to go through relocation, so they shouldn't be in
+ .rofixup sections, and, if they're present in dynamic
+ relocations, they shall be mapped to the NULL address without
+ undergoing relocations. */
+
+ for (c = 0;
+ /* Take advantage of the fact that the loadmap is ordered by
+ virtual addresses. In general there will only be 2 entries,
+ so it's not profitable to do a binary search. */
+ c < map->nsegs && p >= (void*)map->segs[c].p_vaddr;
+ c++)
+ {
+ /* This should be computed as part of the pointer comparison
+ above, but we want to use the carry in the comparison, so we
+ can't convert it to an integer type beforehand. */
+ unsigned long offset = p - (void*)map->segs[c].p_vaddr;
+ /* We only check for one-past-the-end for the last segment,
+ assumed to be the data segment, because other cases are
+ ambiguous in the absence of padding between segments, and
+ rofixup already serves as padding between text and data.
+ Unfortunately, unless we special-case the last segment, we
+ fail to relocate the _end symbol. */
+ if (offset < map->segs[c].p_memsz
+ || (offset == map->segs[c].p_memsz && c + 1 == map->nsegs))
+ return (char*)map->segs[c].addr + offset;
+ }
+
+ /* We might want to crash instead. */
+ return (void*)-1;
+}
+
+# define __RELOC_POINTER(ptr, loadaddr) \
+ (__reloc_pointer ((void*)(ptr), \
+ (loadaddr).map))
+
+#endif /* _BITS_ELF_FDPIC_H */
diff --git a/libc/sysdeps/linux/arm/crtreloc.c b/libc/sysdeps/linux/arm/crtreloc.c
new file mode 100644
index 0000000..560b416
--- /dev/null
+++ b/libc/sysdeps/linux/arm/crtreloc.c
@@ -0,0 +1,144 @@
+/* Copyright (C) 2003, 2004 Free Software Foundation, Inc.
+ written by Alexandre Oliva <aoliva@redhat.com>
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Lesser General Public License as
+published by the Free Software Foundation; either version 2.1 of the
+License, or (at your option) any later version.
+
+In addition to the permissions in the GNU Lesser General Public
+License, the Free Software Foundation gives you unlimited
+permission to link the compiled version of this file with other
+programs, and to distribute those programs without any restriction
+coming from the use of this file. (The GNU Lesser General Public
+License restrictions do apply in other respects; for example, they
+cover modification of the file, and distribution when not linked
+into another program.)
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public
+License along with the GNU C Library; see the file COPYING.LIB. If
+not, see <http://www.gnu.org/licenses/>. */
+
+#ifdef __FDPIC__
+
+#include <sys/types.h>
+#include <link.h>
+
+/* This file is to be compiled into crt object files, to enable
+ executables to easily self-relocate. */
+
+union word {
+ char c[4];
+ void *v;
+};
+
+/* Compute the runtime address of pointer in the range [p,e), and then
+ map the pointer pointed by it. */
+static __always_inline void ***
+reloc_range_indirect (void ***p, void ***e,
+ const struct elf32_fdpic_loadmap *map)
+{
+ while (p < e)
+ {
+ if (*p != (void **)-1)
+ {
+ void *ptr = __reloc_pointer (*p, map);
+ if (ptr != (void *)-1)
+ {
+ void *pt;
+ if ((long)ptr & 3)
+ {
+ unsigned char *c = ptr;
+ int i;
+ unsigned long v = 0;
+ for (i = 0; i < 4; i++)
+ v |= c[i] << 8 * i;
+ pt = (void *)v;
+ }
+ else
+ pt = *(void**)ptr;
+ pt = __reloc_pointer (pt, map);
+ if ((long)ptr & 3)
+ {
+ unsigned char *c = ptr;
+ int i;
+ unsigned long v = (unsigned long)pt;
+ for (i = 0; i < 4; i++, v >>= 8)
+ c[i] = v;
+ }
+ else
+ *(void**)ptr = pt;
+ }
+ }
+ p++;
+ }
+ return p;
+}
+
+/* Call __reloc_range_indirect for the given range except for the last
+ entry, whose contents are only relocated. It's expected to hold
+ the GOT value. */
+attribute_hidden void*
+__self_reloc (const struct elf32_fdpic_loadmap *map,
+ void ***p, void ***e)
+{
+ p = reloc_range_indirect (p, e-1, map);
+
+ if (p >= e)
+ return (void*)-1;
+
+ return __reloc_pointer (*p, map);
+}
+
+#if 0
+/* These are other functions that might be useful, but that we don't
+ need. */
+
+/* Remap pointers in [p,e). */
+static __always_inline void**
+reloc_range (void **p, void **e,
+ const struct elf32_fdpic_loadmap *map)
+{
+ while (p < e)
+ {
+ *p = __reloc_pointer (*p, map);
+ p++;
+ }
+ return p;
+}
+
+/* Remap p, adjust e by the same offset, then map the pointers in the
+ range determined by them. */
+void attribute_hidden
+__reloc_range (const struct elf32_fdpic_loadmap *map,
+ void **p, void **e)
+{
+ void **old = p;
+
+ p = __reloc_pointer (p, map);
+ e += p - old;
+ reloc_range (p, e, map);
+}
+
+/* Remap p, adjust e by the same offset, then map pointers referenced
+ by the (unadjusted) pointers in the range. Return the relocated
+ value of the last pointer in the range. */
+void* attribute_hidden
+__reloc_range_indirect (const struct elf32_fdpic_loadmap *map,
+ void ***p, void ***e)
+{
+ void ***old = p;
+
+ p = __reloc_pointer (p, map);
+ e += p - old;
+ return reloc_range_indirect (p, e, map);
+}
+#endif
+
+#endif /* __FDPIC__ */
diff --git a/libc/sysdeps/linux/arm/find_exidx.c b/libc/sysdeps/linux/arm/find_exidx.c
index 679d90c..cd4d442 100644
--- a/libc/sysdeps/linux/arm/find_exidx.c
+++ b/libc/sysdeps/linux/arm/find_exidx.c
@@ -18,6 +18,23 @@
#include <link.h>
#include <unwind.h>
+#if __FDPIC__
+#include <bits/elf-fdpic.h>
+static __always_inline int
+__dl_addr_in_loadaddr(void *p, struct elf32_fdpic_loadaddr loadaddr)
+{
+ struct elf32_fdpic_loadmap *map = loadaddr.map;
+ int c;
+
+ for (c = 0; c < map->nsegs; c++)
+ if ((void *)map->segs[c].addr <= p &&
+ (char *)p < (char *)map->segs[c].addr + map->segs[c].p_memsz)
+ return 1;
+
+ return 0;
+}
+#endif
+
struct unw_eh_callback_data
{
_Unwind_Ptr pc;
@@ -32,6 +49,26 @@ struct unw_eh_callback_data
static int
find_exidx_callback (struct dl_phdr_info * info, size_t size, void * ptr)
{
+#if __FDPIC__
+ struct unw_eh_callback_data * data;
+ const ElfW(Phdr) *phdr;
+ int i;
+ int match = 0;
+
+ data = (struct unw_eh_callback_data *) ptr;
+ if (__dl_addr_in_loadaddr((void *) data->pc, info->dlpi_addr)) {
+ match = 1;
+ phdr = info->dlpi_phdr;
+ for (i = info->dlpi_phnum; i > 0; i--, phdr++) {
+ if (phdr->p_type == PT_ARM_EXIDX) {
+ data->exidx_start = (_Unwind_Ptr) __RELOC_POINTER(phdr->p_vaddr, info->dlpi_addr);
+ data->exidx_len = phdr->p_memsz;
+ }
+ }
+ }
+
+ return match;
+#else
struct unw_eh_callback_data * data;
const ElfW(Phdr) *phdr;
int i;
@@ -59,6 +96,7 @@ find_exidx_callback (struct dl_phdr_info * info, size_t size, void * ptr)
}
return match;
+#endif
}